The investigator proposes to continuE studies on the following aspects of myocardial metabolism: (1) Regulation of fatty acid oxidation by heart mitochondria, including continued studies on the role of carnitine, competition by other metabolites, etc. (2) Evaluation of the importance of a mechanism for oxidation of unsaturated fatty acids involving combined B-oxidation and gamma oxidation. This latter type of oxidation yields propionate which can be converted to succinate via methylmalonate and requires both biotin and cobamide coenzyme systems. (3) Role of fatty acids in the contractile activity of beating heart cells from adult mammals (rat and human). (4) Regulation of fatty acid and particulate triglyceride up-take by the perfused heart, including the role of proteins (lipoproteins) in membrane and cellular Lipid Transport. Bibliographic references: Quantitative Extraction of Methylmalonic and Succinic Acids and Their Determination by Gas-Liquid Chromatography. C.V. Warner and George V. Vahouny Analytical Biochemistry 67, 122-129 (1975).